My ZA has a 16 marked block & the original ZA 1500 head with standard carbs & exhaust. It pulls a 3.9 axle very well, so I'm not sure if it is down on power. The head, I think, gives a higher CR - because of the smaller chambers(?) I haven't had the head off so have no idea about the pistons. I certainly have single valve springs & haven't got to valve bounce!
As an aside, if I get it on a rolling road, what output at the wheels might be expected? (Any one have the figures for a standard ZA & ZB for comparison?) I don't think I'll need a very big dyno!

Best place to find the right info is Barney Gaylord's website :

mgaguru.com/mgtech/engine/ch100.htm

Here is an excerpt.


The "16" head is nearly identical to the early MGB "18" head, except for a small difference in the Weslake promontory. To have the appropriate compression ratio with the larger combustion chamber the MGA 1622 engine was built with flat top pistons. Pistons in the 1800 to follow were slightly dished. Having been used for only 14 months of production in the MGA, the "16" head is rather rare today. The early "18" head is suitable as a replacement for the MGA 1622 engine. In general, any Austin B-series engine head will bolt onto any B-series engine block (except for the Twin Cams). Pay attention to chamber volume and resulting variations in compression ratio.

Regards,

Andy

We have a 1958 ZB fitted with a later 1622 farina engine but a ZA cylinder head. Clearly the present ZA head is restricting power The query is will the head from a MGB fit. Has anyone carried out this mod or have Knowledge of it.